Crystal Debris vacuumed after pool opened and cleared

[patplh]

Hi, this morning was our first clear pool morning this season - it took 3 days to clear due to leaf debris. This is my 8th year opening with the help of TFP and I had no issues until I vacuumed what I thought was small mounds of dead algae from the pool using a handheld pool vacuum. If you look closely, you'll see it's not algae, but long crystals of something and a lot of it. I've never had this happen before. Any ideas what it is?
Fyi, last year we had an swg installed. Are these salt crystals? Pebble install was in 2016 so there is residual Pebbles, but there are no crystals mixed with the Pebble. We do have Chipmunks who sometimes displace sand into the pool but I don't think the crystals are from the sand. I can easily break the crystals by hand.
Pool is well balanced. I haven't added any new salt, it's currently at 2600, and I plan to raise to 3400. I've only added some calcium, 12% bleach, and muriatic acid. Temp is 60F
Pool closing was done by the same company as the past.

Thanks in advance!
Patty

 

[Razorhog]

Strange. Looks like salt but maybe calcium scaling? Do you have a full set of test results?

 

[patplh]

Hi, these are my results
TC 2
PH 7.5
TA 100
CH 240
CYA 0
SALT 2600
I added a few pounds of Calcium chloride (safe step 7300 deicer) . Same one I've added in previous years and never saw these crystals.
Thanks for responding

 

[mknauss]

Check the ingredients of the de-icer. It may have some 'grip' enhancer in it - ie sand/grit.

 

[Razorhog]

Looks like gypsum (Calcium Sulfate)

Sediment/Crystals on pool bottom

 

[mknauss]

Good catch!

Do you use Dry Acid in the pool?

 

[patplh]

Hi thanks for all the responses and the link to the thread. Such a weird situation since we never had these crystals before. I don't use dry acid. I've only used liquid muriatic acid from lowes, which when added to the crystals does cause it to fizz. So the general idea from the other thread is that sulfur is in the water.. Probably as an additive from a chemicals I added?
I'll just keep vacuuming it out then? Calcium does leach out of our rock wall too as efflorescence, but this has been happening for years and we haven't seen there crystals until now.
So weird. I'm guessing I should continue to add more calcium since I'm borderline low with a plaster (wetedge Pebble) pool.
Thanks

 

[Divin Dave]

Ive seen similar things pup up a few times since Ive been around

Most likely calcium sulfate crystals.
Large crystals in my pool

 

[patplh]

Thanks. Still not sure where the sulfite is coming from, but vacuuming out doesn't seem to be too hard.
But those pictures of the crystals in the other post are amazing.